I have to agree with the previous posting, the likelihood of an upgrade is slim at this point. But, never say never!
You might want to ask for a guarantee stateroom for your next cruise. You would have to wait until your cruise documents arrive, 1-2 weeks before your departure, to find out your exact cabin number, but in almost 10 years as a travel agent/cruise specialist, I have had very few clients with guarantee stateroom reservations that DON'T get a nice, usually big, upgrade on their stateroom. The guarantee staterooms are usually less expensive, too.
I actually don't think that staterooms that are further to the front or back of the ship are bad. You would have fewer people walking by your stateroom, so your stateroom is more quiet and private.